openEPDA CDF format


This document contains draft description of the Chip Description File (CDF), which is used as a reference for electrical pads and optical ports positions for the measurements to be performed on Photonic Integrated Circuits (PIC). The latest version is 0.3.


CDF is a configuration file that contains data with design coordinates of the chip inputs and outputs (IO) (both electrical and optical). Therefore it is linked to a specific design (cell), meaning that for every new die design, also the applicable CDF needs to be composed.

The format of the file is meant to be human readable and intuitive in its structure. It provides all necessary information starting from cell design identification data, which is to be crosschecked with other configuration files (e.g. MDF), up to the IO coordinates themselves.

Relation to netlist and MDF

There are multiple standards used to describe a simulation on an electronic circuit. Let’s have a look how one of the most popular such formats – SPICE – is organized. It usually consists of two sections, the netlist and the analyses section. The former one describes the circuit, its elements, parameters, and connections. The latter – Analyses part – tells the simulator what kind of simulation is to be run on the circuit.

With introducing CDF and MDF, openEPDA makes the same distinction between the circuit itself and measurements/simulations to be performed on this circuit.

Now, the circuit can be described in different ways. For fabrication, a representation in the form of a mask set is required (GDSII or OASIS format). For circuit simulation, or from a designer’s perspective, a circuit is a set of interconnected BBs representing a netlist. For the measurements, a black box description of the circuit is sufficient: only the names and location of the inputs/outputs of the circuit are needed. CDF is the format which describes this last representation.


openEPDA CDF format is available under CC BY-SA 4.0 license.

This is Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0). See full license text here: CC BY-SA 4.0.

More details on openEPDA view on standards licensing are available on Licensing policy page.


The standard specifies the contents of the file, which means which attributes have to be defined in the file. Some attributes are required and some are optional. There are also reserved attributes which start with an underscore.

Besides the contents, the standard also defines the actual representation of the data, which is YAML format. More information regarding the YAML syntax can be found here:


openEPDA provides online validators for the Chip Description Files, go to this page.